User equipment and method for transmitting a data stream to an evolved node b

ABSTRACT

In a wireless network, a user equipment (UE) can communicate with an Evolved Node B (eNodeB). During at least some times, the UE transmits a data stream to the eNodeB, over one of several available antenna states on the UE. The antenna states can include one or more tuning states for each antenna port on the UE. At predetermined times, which can be periodic, the UE ceases transmission of the data stream, transmits a test signal sequentially over each of its antenna states, receives a signal back from the eNodeB indicating which of the antenna states provides the strongest signal, and switches to the indicated antenna state. After switching, the UE can resume transmission of the data stream over the indicated antenna state. In some examples, the UE can repeat the antenna tuning/retuning process periodically.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/575,448, filed Dec. 18, 2014, which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

Embodiments pertain to operations and communications performed byelectronic devices in wireless networks. Some embodiments relate toperiodic antenna retuning in a user equipment (UE).

BACKGROUND

A user equipment (UE) can communicate with an Evolved Node B (eNodeB).It is desirable to provide a strong signal at the eNodeB from the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a user equipment (UE) configured to transmita data stream to an Evolved Node B (eNodeB), in accordance with someembodiments.

FIG. 2 shows an example of a method for transmitting a data stream froma UE to an eNodeB, in accordance with some embodiments.

FIG. 3 shows an example of a transmission and reception sequence forcircuitry, in accordance with some embodiments.

FIG. 4 shows an example of an uplink Long Term Evolution (LTE) framestructure, with a Sounding Reference Signal (SRS) symbol identified, inaccordance with some embodiments.

FIG. 5 shows an example of an uplink FDD LTE with antenna tuningsubframes, in accordance with some embodiments.

FIG. 6 shows an example of a TDD LTE with antenna tuning subframes, inaccordance with some embodiments.

FIG. 7 shows an example of a downlink control indicator (DCI) format, inaccordance with some embodiments.

FIG. 8 shows an example of an SRS request, in accordance with someembodiments.

FIG. 9 shows an example of an SRS report field, in accordance with someembodiments.

FIG. 10 shows an example of an antenna tuning procedure between theeNodeB and the UE, for the physical layer approach, in accordance withsome embodiments.

FIG. 11 shows an example of an upper layer antenna tuning configurationmessage, in accordance with some embodiments.

FIG. 12 shows an example of an LTE closed loop antenna tuning algorithmflow (upper layer option), in accordance with some embodiments.

FIG. 13 shows four examples of locations where open loop antenna tuningzones (ATZ) can be positioned in a generic FDD LTE network, inaccordance with some embodiments.

FIG. 14 shows three examples of locations where open loop antenna tuningzones (ATZ) can be positioned in a generic TDD LTE network, inaccordance with some embodiments.

FIG. 15 shows an example of antenna tuning states in an FDD LTE network,in accordance with some embodiments.

FIG. 16 shows an example of antenna tuning states in a TDD LTE network,in accordance with some embodiments.

FIG. 17 illustrates an example of a mobile device, in accordance withsome embodiments.

FIG. 18 is a block diagram illustrating an example computer systemmachine upon which any one or more of the methodologies herein discussedcan be run, in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments can incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentscan be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 shows an example of a user equipment (UE) 100 configured totransmit a data stream to an Evolved Node B (eNodeB) 102. Examples of asuitable UE 100 can include a cellular telephone, a smart phone, acellular modem, a tablet, a personal computer, or a machine-to-machine(M2M)/machine type communication (MTC) device, such as an automotivedevice or a sensor that can communicate with a cellular network. The UE100 from FIG. 1 is but one example; other suitable UE configurations canalso be used.

The UE 100 can include at least one antenna 104A-B. In the example ofFIG. 1, the UE 100 includes a plurality 104 of antennas 104A-B; in otherexamples, the UE 100 can include more than two antennas. Each antenna104A-B can be capable of transmitting data from the data stream to theeNodeB 102 at one of a plurality of selectable tuning states.

The UE 100 can include a plurality 106 of antenna ports 106A-B. In someexamples, each antenna port 106A-B is connectable to a respectiveantenna 104A-B. In some examples, the antenna ports 106A-B can be formedas part of a system-on-chip. In these examples, the antennas 104A-B canbe formed external to the system-on-chip, and attached to respectiveantenna ports 106A-B on the system-on-chip. In some examples, eachantenna 104A-B can be electrically coupled to a respective antenna port106A-B. The combination of antenna ports 106A-B and tuning states canform a plurality of selectable antenna states for the UE 100. In someexamples, each antenna state can include one or more tuning states foreach antenna port 106A-B. In some examples, the number of antenna statesexceeds a number of antenna ports 106A-B on the UE 100.

A plurality 108 of antenna tuner elements 108A-B can be electricallycoupled to respective antennas 104A-B through respective antenna ports106A-B. In the example of FIG. 1, the UE 100 includes two antenna ports106A-B; in other examples, the UE 100 can include more than two antennaports. Each antenna tuner element 108A-B can receive a tuner controlsignal 110A-B that specifies a selected tuning state for the respectiveantenna 104A-B. Each antenna tuner element 108A-B can further receive aradio frequency (RF) signal 112A-B corresponding to data from the datastream. In these examples, the antenna tuner element 108A-B can beintegrated into the system-on-chip or remain as external componentswhile being attached to respective antenna ports 106A-B on thesystem-on-chip.

The UE 100 can include at least one transceiver 114A-B. In the exampleof FIG. 1, the UE 100 includes a plurality 114 of transceivers 114A-B.Each transceiver 114A-B can be electrically coupled to a respectiveantenna tuner element 108A-B. In some examples, at least one transceiver114A-B has a radio frequency front end (RFFE) that can apply at leastone of a selectable impedance or a selectable aperture to a respectiveantenna port 106A-B. In these examples, the combination of antenna ports106A-B and selected impedances or selected apertures can form theplurality of selectable antenna states for the UE 100. Each transceiver114A-B can also receive data from the data stream and generate therespective RF signal 112A-B.

A multiple-input and multiple-output (MIMO) modem 116 can beelectrically coupled to the plurality 108 of antenna tuner elements108A-B. The MIMO modem 116 can select one of the plurality 114 oftransceivers 114A-B, provide data from the data stream to the selectedtransceiver 114A-B, and generate the tuner control signal 110A-B for theselected transceiver 114A-B.

In some examples, the UE can include circuitry, which can include theantenna tuner elements 108A-B, the transceivers 114A-B, and/or the MIMOmodem 116.

FIG. 2 shows an example of a method 200 for transmitting a data streamfrom a UE, such as 100 (FIG. 1) to an eNodeB, such as 102 (FIG. 1). Insome examples, the method 200 can be executed on a UE. In some examples,the method can be executed by circuitry on the UE, such as MIMO modem116 (FIG. 1). In some examples, the method 200 can be executed by anon-transitory computer-readable medium containing instructions which,when executed, perform operations to configure a UE to transmit a datastream to an eNodeB. In some examples, the UE can include a plurality ofantenna states configured for transmitting from the UE. The method 200is but one example; other suitable methods can also be used.

At 202, method 200 can transmit to the eNodeB a first portion of thedata stream over a first antenna state, of the plurality of antennastates. At 204, method 200 can sequentially transmit to the eNodeB atest signal over each antenna state in the plurality. In some examples,the test signal can be the same for each antenna state. In otherexamples, the test signal can differ for at least two of the antennastates. In some examples, the test signal can include one or more pulsesat a specified frequency. At 206, method 200 can receive from the eNodeBan indication that the test signal transmitted on a second antennastate, of the plurality of antenna states, is stronger at the eNodeBthan the test signal transmitted on the first antenna state. In someexamples, the indication from the eNodeB can specify which of theantenna states provides the strongest reception at the eNodeB. In someexamples, the indication from the eNodeB can specify that the secondantenna state provides the strongest reception at the eNodeB. At 208,method 200 can transmit to the eNodeB a second portion of the datastream on the second antenna state.

In some examples, the UE can further include at least one antenna port.In some of these examples, the UE can further include at least onetransceiver having a radio frequency front end (RFFE) that can apply aselectable tuning state to a respective antenna port. In these examples,each antenna state can comprise a unique combination of antenna port andtuning state. In these examples, the RFFE can select each tuning stateby applying at least one of a selectable impedance or a selectableaperture to the respective antenna port. In some of these examples, thenumber of antenna states in the plurality can exceed a number of antennaports on the UE. In some examples, the UE can further include at leastone antenna electrically coupled to a respective antenna port.

In some examples, the sequential transmission can begin and end at firstand second predetermined times during the data stream transmission. Insome of these examples, between third and fourth predetermined timesduring the data stream transmission, the UE can sequentially transmit tothe eNodeB a test signal on each antenna state in the plurality. In someof these examples, the UE can receive from the eNodeB an indication thata third antenna state, of the plurality of antenna states, provides thestrongest of the received test signals at the eNodeB. In some of theseexamples, the UE can transmit to the eNodeB a third portion of the datastream on the third antenna state.

In some examples, elements 202-208 can be repeated periodically, forinstance, at predetermined times during the data stream transmission.

In a specific example, in a wireless network, a UE, such as 100 (FIG.1), can communicate with an eNodeB, such as 102 (FIG. 1). In thisexample, during at least some times, the UE 100 transmits a data streamto the eNodeB 102 over one of several available antenna states on the UE100. In this example, the antenna states can include one or more tuningstates for each antenna port, such as 106A-B (FIG. 1) on the UE 100. Inthis example, at predetermined times, which can be periodic, the UE 100ceases transmission of the data stream, transmits a test signalsequentially on each of its antenna states, receives a signal back fromthe eNodeB 102 indicating which of the antenna states provides thestrongest signal, and switches to the indicated antenna state. Afterswitching, the UE 100 can resume transmission of the data stream overthe indicated antenna state. In some examples, the UE 100 can repeat theantenna tuning/retuning process periodically.

Updating the UE 100 to use the antenna state that produces the strongestsignal at the eNodeB 102 can improve the performance of the UE 100,particularly if the UE 100 moves with respect to the eNodeB 102. Forexample, if the UE 100 is a cellular telephone, updating the cellulartelephone to use the antenna state that produces the strongest signal atthe eNodeB 102 can improve the link quality between the eNodeB 102 andthe UE 100, and in some cases can help reduce instances of dropped callsor improve the link data rate (throughput). In some examples, tuning theUE antenna(s), such as 104A-B (FIG. 1), using feedback from the eNodeB102 can be applied to Long Term Evolution (LTE) Frequency DivisionDuplex (FDD) and Time Division Duplex (TDD) networks and can beimplemented with changes to the existing LTE standard.

Using feedback from the eNodeB 102 allows the UE 100 to tune itsantennas 104A-B in a closed-loop manner. This represents a significantimprovement over tuning protocols that operate in an open-loop mannerand do not use feedback from the eNodeB 102. Some examples of open-loopantenna tuning protocols can use a number of passive antenna elements,corresponding to a multiple-input and multiple-output (MIMO) ordersupported by a UE category. Some examples of open-loop antenna tuningprotocols can integrate switch diversity configurations. Some examplesof open-loop antenna tuning protocols can drive antenna selection byexternal sensor inputs or by an antenna-selective precoding matrixfeedback mechanism available in a technical specification, such as theLTE Release 10 specification. Some examples of open-loop antenna tuningprotocols can couple the number of UE antenna tuning states to thenumber of UE antenna ports, such as 106A-B (FIG. 1), thereby restrictingthe number of available UE antenna tuning states. By decoupling the UEantenna states from the number of UE antenna ports 106A-B, theclosed-loop tuning protocol discussed herein can increase the number ofavailable antenna tuning states beyond a fixed number of MIMO modemtransceiver elements, such as 114A-B (FIG. 1), which correspond to thenumber of antenna ports 106A-B. The closed-loop tuning protocoldiscussed herein differs from digital beamforming in that theclosed-loop tuning protocol discussed herein can use analog circuitry tomodify the antenna response of the UE by searching over the analog RFstates of the tunable antenna.

FIG. 3 shows an example of a transmission and reception sequence 300 forcircuitry, such as MIMO modem 116 (FIG. 1). The sequence 300 of FIG. 3is but one example; other sequences can also be used.

At 302, the MIMO modem can transmit to the eNodeB a first portion of thedata stream over a first antenna state, of the plurality of antennastates. The first portion transmission can cease at a firstpredetermined time.

At 304, the MIMO modem can sequentially transmit to the eNodeB a testsignal over each antenna state in the plurality. The antenna states caninclude the combinations of antenna and tuning state, and/orcombinations of antenna port and tuning state. The sequentialtransmission can begin at a second predetermined time.

At 306, the MIMO modem can receive from the eNodeB an indication thatthe test signal transmitted over a second antenna state, of theplurality of antenna states, is stronger than the test signaltransmitted over the first antenna state. In some examples, the MIMOmodem can receive from the eNodeB an indication that a second antennastate, of the plurality of antenna states, provides the strongest of thereceived test signals at the eNodeB. The receiving can begin at a thirdpredetermined time.

At 308, the MIMO modem can transmit to the eNodeB a second portion ofthe data stream over the second antenna state. The second portiontransmission can begin at a fourth predetermined time. In some examples,the first and second antenna states are different; in other examples,the first and second antenna states are the same.

In some examples, the sequence 300 of FIG. 3 can repeat periodically.For instance, the MIMO modem can cease transmitting to the eNodeB thesecond portion of the data stream over the second antenna state at afifth predetermined time. At 310, the MIMO modem can sequentiallytransmit to the eNodeB a test signal over each antenna state in theplurality beginning at a sixth predetermined time. At 312, the MIMOmodem can receive an indication that the test signal transmitted over asecond antenna state, of the plurality of antenna states, is strongerthan the test signal transmitted over the first antenna state. In someexamples, the MIMO modem can receive from the eNodeB an indication thata third antenna state, of the plurality of antenna states, provides thestrongest of the received test signals at the eNodeB at a seventhpredetermined time. At 314, the MIMO modem can transmit to the eNodeB athird portion of the data stream over the third antenna state beginningat an eighth predetermined time. In some examples, the second and thirdantenna states are different; in other examples, the second and thirdantenna states are the same. One of ordinary skill in the art willreadily understand that FIG. 3 is not drawn to scale.

In some examples, each antenna state includes a combination of antennaand tuning state for the antenna. In some examples, each antenna stateis a unique combination of antenna and tuning state. In some examples,two different antenna states include the same antenna and differenttuning states. In some examples, two different antenna states includedifferent antennas and the same tuning state. In some examples, twodifferent antenna states include different antennas and different tuningstates.

The following discussion and figures and describe specific examples ofhow a wireless network would implement the antenna retuning describedabove and shown in FIGS. 1-3. For instance, the communication protocolsof FIGS. 1-3 can be incorporated into a wireless network standard thatgoverns communication between UEs and eNodeBs in the network.

FIG. 4 shows an example of an uplink Long Term Evolution (LTE) framestructure, with a Sounding Reference Signal (SRS) symbol identified. Theresource element allocations shown in FIG. 4 are but one example, andcan vary as needed.

Prior to each dedicated SRS transmission that is part of theeNodeB-controlled antenna tuning process, the UE selects a new antennastate and transmits the dedicated SRS. Such a subframe is termed theAntenna Tuning Subframe (ATSF). For example, if the UE includes fourantennas and three tuning states per antenna (totaling 3⁴, or 81,antenna states), then the UE performs 81 SRS transmissions to theeNodeB, with one SRS transmission in each antenna state. Upon completionof the SRS transmissions, the eNodeB has a set of measurements of theuplink SRS transmissions across a number of UE antenna states and cansignal back to the UE the preferred state. The eNodeB can also signalthe Rank Indicator and Precoding Matrix (RI-PMI) information associatedwith the preferred UE antenna state. In some examples, the eNodeB canadditionally signal other information about the tuning selection ormeasurements made at the eNodeB to enhance performance.

FIG. 5 shows an example of an uplink FDD LTE with Antenna TuningSubframes (ATSF). FIG. 6 shows an example of a TDD LTE with AntennaTuning Subframes (ATSF). FIGS. 5 and 6 show dedicated SRS transmissionsscheduled within the configured SRS channel, which can allow the eNodeBto perform individual measurements of uplink transmissions as a functionof different UE antenna tuning states. The eNodeB can assign the fullbandwidth or a portion of the bandwidth for the dedicated SRStransmissions, as needed.

In some examples, the antenna retuning process discussed herein isaccomplished with changes only in the physical layer. This is referredto as the physical layer approach, which is shown in FIGS. 7-10 anddiscussed below.

FIG. 7 shows an example of a Downlink Control Indicator (DCI) format. Inthe example of FIG. 7, a DCI message, transmitted to the UE in thePhysical Downlink Control Channel (PDCCH), can be modified to a newformat (based on Format 4). The eNodeB can send an SRS report field tothe UE using the FDD format of FIG. 7, or another suitable format. TheSRS report field can begin the antenna tuning process and can maintain acounter of the Antenna Tuning Subframes (ATSF). FIG. 8 shows an exampleof an SRS request. FIG. 9 shows an example of an SRS report field. TheSRS request and SRS report field of FIG. 8-9 are merely examples; othersuitable SRS requests and SRS report fields can also be used.

FIG. 10 shows an example of an antenna tuning procedure 1000 between theeNodeB and the UE, for the physical layer approach. The antenna tuningprocedure 1000 is but one example; other suitable antenna tuningprocedures can also be used.

At 1002, the SRS channel and the dedicated SRS configuration for the UEvia upper layer messaging are established. The establishing can beperformed by the eNodeB, by the UE, or by an additional elementconnected to the wireless network.

At 1004, the eNodeB sends the modified DCI Format 4 (FIG. 7) message tothe UE with the SRS Request field set to select one of thepre-configured SRS parameter sets and with the SRS Report field set to111 to trigger the start of the antenna tuning process at the UE.

At 1006, upon receiving the message, the UE tunes its antenna to a newantenna state, the UE transmits the dedicated SRS, and the UE tunes itsantenna state back to its previous operating antenna state. The eNodeBscheduler implementation can help reduce errors in the downlink by notscheduling PDSCH transmissions to the UE during the subframes thatcontain dedicated SRS transmissions used in this antenna tuningprocedure.

At 1008, the eNodeB sends a DCI Format 4 message to the UE, to triggersthe UE to advance to the next antenna state.

At 1010 and 1012, the eNodeB and UE repeat elements 1006 and 1008 untilthere are N antenna state transmissions from the UE to the eNodeB. N canbe less than or equal to the maximum integer that can be represented bythe number of bits of the SRS report field (FIG. 9) minus 1.

As the eNodeB collects the dedicated SRS transmissions over N UE antennatuning states, the eNodeB computes a figure of merit that allows it toselect the optimal UE antenna tuning state. At 1014, the eNodeBtransmits the modified DCI Format 4 message to the UE with the SRSReport field set to the ATSF index corresponding to the eNodeB's choiceof the optimal UE antenna tuning state along with the RI-PMI informationcorresponding to this UE antenna tuning state. The UE then tunes itsantenna to the state indicated by the eNodeB, re-synchronizes to thechannel, and continues operation with the new antenna state.

In some examples, the antenna retuning process discussed herein isaccomplished with changes only in the MAC layer specification. The MAClayer specification approach would reuse the existing sounding procedurein the physical layer available in LTE Release 10. This is referred toas the upper layer approach, which is shown in FIGS. 11-12 and discussedbelow.

FIG. 11 shows an example of an upper layer antenna tuning configurationmessage. In the example of FIG. 11, the upper layer messaging optioninitiates and terminates the antenna tuning process with the upper layerconfiguration message and utilizes the already existing dedicated SRSprocedures for the UE via the DCI Format 4 sounding trigger. The MAClayer approach differs from the physical layer approach by having anadditional delay in starting and terminating the antenna tuningprocedures via the upper layers, and by the ability to accommodate moreUE antenna tuning states due to a larger bit width of the ATSF counter.

FIG. 12 shows an example of an antenna tuning procedure 1200 between theeNodeB and the UE, for the upper layer approach.

At 1202, the SRS channel and the dedicated SRS configuration for the UEvia upper layer messaging are established. The establishing can beperformed by the eNodeB, by the UE, or by an additional elementconnected to the wireless network.

At 1204, the eNodeB sends an upper layer antenna tuning configurationmessage, such as the message of FIG. 11, to the UE. The message sets thefield srs-atsfCountReset to TRUE.

At 1206, the eNode B sends a DCI Format 4 message with an SRS request tothe UE with the SRS Request field set to select one of thepre-configured SRS parameter sets.

At 1208, upon receiving the message, the UE tunes its antenna to a newantenna state, UE transmits the dedicated SRS, and tunes its antennastate back to its previous operating antenna state.

At 1210, 1212, and 1214, the eNodeB and UE repeat elements 1206 and 1208and 1008 until there are N antenna state transmissions from the UE tothe eNodeB. In this example, N can be less than or equal 1024.

At 1216, the eNodeB sends an upper layer antenna tuning configurationmessage, such as the message of FIG. 11, to the UE. The message sets thefield srs-atsfCountReset to FALSE.

As the eNodeB collects the dedicated SRS transmissions over N UE antennatuning states, the eNodeB computes a figure of merit that allows it toselect the optimal UE antenna tuning state. At 1218, the eNodeBtransmits the modified DCI Format 4 message to the UE communicating theeNodeB's choice of the optimal UE antenna tuning state along with theRI-PMI information corresponding to this UE antenna tuning state. The UEthen tunes its antenna to the state indicated by the eNodeB,re-synchronizes to the channel, and continues operation with the newantenna state.

There can be instances when a network does not support eNodeB control,for example, in a legacy network. For these instances, a legacy fallbackmode for antenna tuning can allow a UE to tune its antennas, usingsignals from the eNodeB, while operating in a legacy network. Todetermine an optimal tuning state for each antenna, the UE seeksintervals in the LTE downlink to select a new tuning state and toreceive the known reference signal from the eNodeB. These intervals aretermed antenna tuning zones (ATZ).

FIG. 13 shows four examples of locations where open loop antenna tuningzones (ATZ) can be positioned in a generic FDD LTE network; otherexamples can also be used.

Element 1302 shows an example of an ATZ over a partial subframe. At1302, the UE receives the control information in the PDCCH, determinesno data is scheduled in the PDSCH of the same subframe, and designatesall remaining symbols as ATZ.

Element 1304 shows an example of an ATZ over a full subframe. At 1304,the UE determines from prior PDCCH information that it does not expectany control data from the eNodeB in this subframe, and it designates theentire subframe as ATZ.

Element 1306 shows an example of an ATZ over a single time slot. At1306, the UE receives both the PDCCH and the remaining symbols in thefirst time slot of the subframe, determines that no data is expected inthe second time slot, and it designates the second time slot of thesubframe as ATZ.

Element 1308 shows an example of an ATZ over an almost blank subframe(ABS). At 1308, the UE is assumed to be operating on a networksupporting enhanced inter-cell interference cancellation (eICIC), and itdesignates the entire ABS as ATZ.

FIG. 14 shows three examples of locations where open loop antenna tuningzones (ATZ) can be positioned in a generic TDD LTE network; otherexamples can also be used.

Element 1402 shows an example of an ATZ over a partial subframe. At1402, the UE receives the control information in the PDCCH, determinesno data is scheduled in the PDSCH of the same subframe, and designatesall remaining symbols as ATZ.

Element 1404 shows an example of an ATZ over a full subframe. At 1404,the UE determines from prior PDCCH information that it does not expectany control data from the eNodeB in this subframe, and it designates theentire subframe as ATZ.

Element 1406 shows an example of an ATZ over an almost blank subframe(ABS). At 1406, the UE is assumed to be operating on a networksupporting enhanced inter-cell interference cancellation (eICIC), and itdesignates the entire ABS as ATZ.

FIG. 15 shows an example of antenna tuning states in an FDD LTE network.This is but one example; other suitable antenna tuning states can alsobe used.

At 1502, during the current LTE frame (Frame0), the UE receives all datascheduled for UE utilizing the current antenna tuning state.

At 1504, during an ATZ, the UE determines that a new antenna tuningstate is preferred over the current antenna tuning state. During theATZ, the UE selects a new antenna tuning state, receives the referencesignal sequence from the eNodeB, estimates the channel fadingcoefficients, and calculates the antenna tuning optimization metricbased on these coefficients. To improve the performance of the metric,the UE can also receive and demodulate the PDCCH (in the case of ATZover a full subframe), and/or the UE can receive and demodulate otherusers' data in the PDSCH (providing the UE with a more robust estimateof the SINR). Upon completion of the ATZ, the UE tunes the antenna backto its current state and completes the reception of the current LTEframe. Any tuning transition time can be included within the ATZ inorder to enable the UE to receive all scheduled data for the UE.

At 1506, the UE completes the reception of Frame0, tunes the antenna tothe new state, synchronizes to the cell during the next available SSSand PSS, and continues operation with the new antenna state.

FIG. 16 shows an example of antenna tuning states in a TDD LTE network.This is but one example, other suitable antenna tuning states can alsobe used.

At 1602, during the current LTE frame (Frame0), the UE receives all datascheduled for UE utilizing the current antenna tuning state.

At 1604, during an ATZ, the UE determines that a new antenna tuningstate is preferred over the current antenna tuning state. During theATZ, the UE selects a new antenna tuning state, receives the referencesignal sequence from the eNodeB, estimates the channel fadingcoefficients, and calculates the antenna tuning optimization metricbased on these coefficients. To improve the performance of the metric,the UE can also receive and demodulate the PDCCH (in the case of ATZover a full subframe), and/or the UE can receive and demodulate otherusers' data in the PDSCH (providing the UE with a more robust estimateof the SINR). Upon completion of the ATZ, the UE tunes the antenna backto its current state and completes the reception of the current LTEframe. Any tuning transition time can be included within the ATZ inorder to enable the UE to receive all scheduled data for the UE.

At 1606, the UE completes the reception of Frame0, tunes the antenna tothe new state, synchronizes to the cell during the next available SSSand PSS, and continues operation with the new antenna state.

Although the preceding examples of wireless network connections wereprovided with specific reference to 3GPP LTE/LTE-A, IEEE 802.11, andBluetooth communication standards, it will be understood that a varietyof other WWAN, WLAN, and WPAN protocols and standards can be used inconnection with the techniques described herein. These standardsinclude, but are not limited to, other standards from 3GPP (e.g., HSPA+,UMTS), IEEE 802.16 (e.g., 802.16p), or Bluetooth (e.g., Bluetooth 4.0,or like standards defined by the Bluetooth Special Interest Group)standards families. Other applicable network configurations can beincluded within the scope of the presently described communicationnetworks. It will be understood that communications on suchcommunication networks can be facilitated using any number of personalarea networks, LANs, and WANs, using any combination of wired orwireless transmission mediums.

The embodiments described above can be implemented in one or acombination of hardware, firmware, and software. Various methods ortechniques, or certain aspects or portions thereof, can take the form ofprogram code (i.e., instructions) embodied in tangible media, such asflash memory, hard drives, portable storage devices, read-only memory(ROM), random-access memory (RAM), semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)), magnetic disk storagemedia, optical storage media, and any other machine-readable storagemedium or storage device wherein, when the program code is loaded intoand executed by a machine, such as a computer or networking device, themachine becomes an apparatus for practicing the various techniques.

A machine-readable storage medium or other storage device can includeany non-transitory mechanism for storing information in a form readableby a machine (e.g., a computer). In the case of program code executingon programmable computers, the computing device can include a processor,a storage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device. One or more programs that can implementor utilize the various techniques described herein can use anapplication programming interface (API), reusable controls, and thelike. Such programs can be implemented in a high level procedural orobject oriented programming language to communicate with a computersystem. However, the program(s) can be implemented in assembly ormachine language, if desired. In any case, the language can be acompiled or interpreted language, and combined with hardwareimplementations.

FIG. 17 illustrates an example of a mobile device 1700. The mobiledevice 1700 can be a user equipment (UE), a mobile station (MS), amobile wireless device, a mobile communication device, a tablet, ahandset, or other type of mobile wireless computing device. The mobiledevice 1700 can include one or more antennas 1708 within housing 1702that are configured to communicate with a hotspot, base station (BS), anevolved NodeB (eNodeB), or other type of WLAN or WWAN access point. Themobile device 1700 can be configured to communicate using multiplewireless communication standards, including standards selected from 3GPPLTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and Wi-Fistandard definitions. The mobile device 1700 can communicate usingseparate antennas for each wireless communication standard or sharedantennas for multiple wireless communication standards. The mobiledevice 1700 can communicate in a WLAN, a WPAN, and/or a WWAN.

FIG. 17 also shows a microphone 1720 and one or more speakers 1712 thatcan be used for audio input and output from the mobile device 1700. Adisplay screen 1704 can be a liquid crystal display (LCD) screen, orother type of display screen such as an organic light emitting diode(OLED) display. The display screen 1704 can be configured as a touchscreen. The touch screen can use capacitive, resistive, or another typeof touch screen technology. An application processor 1714 and a graphicsprocessor 1718 can be coupled to internal memory 1716 to provideprocessing and display capabilities. A non-volatile memory port 1710 canalso be used to provide data input/output options to a user. Thenon-volatile memory port 1710 can also be used to expand the memorycapabilities of the mobile device 1700. A keyboard 1706 can beintegrated with the mobile device 1700 or wirelessly connected to themobile device 1700 to provide additional user input. A virtual keyboardcan also be provided using the touch screen. A camera 1722 located onthe front (display screen) side or the rear side of the mobile device1700 can also be integrated into the housing 1702 of the mobile device1700.

FIG. 18 is a block diagram illustrating an example computer systemmachine 1800 upon which any one or more of the methodologies hereindiscussed can be run. Computer system machine 1800 can be embodied asthe local UE 106, the remote UE 108, or any other computing platformdescribed or referred to herein. In alternative embodiments, the machineoperates as a standalone device or can be connected (e.g., networked) toother machines. In a networked deployment, the machine can operate inthe capacity of either a server or a client machine in server-clientnetwork environments, or it can act as a peer machine in peer-to-peer(or distributed) network environments. The machine can be a personalcomputer (PC) that may or may not be portable (e.g., a notebook or anetbook), a tablet, a set-top box (STB), a gaming console, a PersonalDigital Assistant (PDA), a mobile telephone or smartphone, a webappliance, a network router, switch or bridge, or any machine capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that machine. Further, while only a single machine isillustrated, the term “machine” shall also be taken to include anycollection of machines that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies discussed herein.

Example computer system machine 1800 includes a processor 1802 (e.g., acentral processing unit (CPU), a graphics processing unit (GPU) orboth), a main memory 1804 and a static memory 1806, which communicatewith each other via an interconnect 1808 (e.g., a link, a bus, etc.).The computer system machine 1800 can further include a video displayunit 1810, an alphanumeric input device 1812 (e.g., a keyboard), and auser interface (UI) navigation device 1814 (e.g., a mouse). In oneembodiment, the video display unit 1810, input device 1812 and UInavigation device 1814 are a touch screen display. The computer systemmachine 1800 can additionally include a storage device 1816 (e.g., adrive unit), a signal generation device 1818 (e.g., a speaker), anoutput controller 1832, a power management controller 1834, and anetwork interface device 1820 (which can include or operably communicatewith one or more antennas 1830, transceivers, or other wirelesscommunications hardware), and one or more sensors 1828, such as a GlobalPositioning Sensor (GPS) sensor, compass, location sensor,accelerometer, or other sensor.

The storage device 1816 includes a machine-readable medium 1822 on whichis stored one or more sets of data structures and instructions 1824(e.g., software) embodying or utilized by any one or more of themethodologies or functions described herein. The instructions 1824 canalso reside, completely or at least partially, within the main memory1804, static memory 1806, and/or within the processor 1802 duringexecution thereof by the computer system machine 1800, with the mainmemory 1804, static memory 1806, and the processor 1802 alsoconstituting machine-readable media.

While the machine-readable medium 1822 is illustrated in an exampleembodiment to be a single medium, the term “machine-readable medium” caninclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) that storethe one or more instructions 1824. The term “machine-readable medium”shall also be taken to include any tangible medium that is capable ofstoring, encoding or carrying instructions for execution by the machineand that cause the machine to perform any one or more of themethodologies of the present disclosure or that is capable of storing,encoding or carrying data structures utilized by or associated with suchinstructions.

The instructions 1824 can further be transmitted or received over acommunications network 1826 using a transmission medium via the networkinterface device 1820 utilizing any one of a number of well-knowntransfer protocols (e.g., HTTP). The term “transmission medium” shall betaken to include any intangible medium that is capable of storing,encoding, or carrying instructions for execution by the machine, andincludes digital or analog communications signals or other intangiblemedium to facilitate communication of such software.

It should be understood that the functional units or capabilitiesdescribed in this specification can have been referred to or labeled ascomponents or modules, in order to more particularly emphasize theirimplementation independence. For example, a component or module can beimplemented as a hardware circuit comprising custom very-large-scaleintegration (VLSI) circuits or gate arrays, off-the-shelf semiconductorssuch as logic chips, transistors, or other discrete components. Acomponent or module can also be implemented in programmable hardwaredevices such as field programmable gate arrays, programmable arraylogic, programmable logic devices, or the like. Components or modulescan also be implemented in software for execution by various types ofprocessors. An identified component or module of executable code can,for instance, comprise one or more physical or logical blocks ofcomputer instructions, which can, for instance, be organized as anobject, procedure, or function. Nevertheless, the executables of anidentified component or module need not be physically located together,but can comprise disparate instructions stored in different locationswhich, when joined logically together, comprise the component or moduleand achieve the stated purpose for the component or module.

Indeed, a component or module of executable code can be a singleinstruction, or many instructions, and can even be distributed overseveral different code segments, among different programs, and acrossseveral memory devices. Similarly, operational data can be identifiedand illustrated herein within components or modules, and can be embodiedin any suitable form and organized within any suitable type of datastructure. The operational data can be collected as a single data set,or can be distributed over different locations including over differentstorage devices, and can exist, at least partially, merely as electronicsignals on a system or network. The components or modules can be passiveor active, including agents operable to perform desired functions.

Additional examples of the presently described method, system, anddevice embodiments include the following, non-limiting configurations.Each of the following non-limiting examples can stand on its own, or canbe combined in any permutation or combination with any one or more ofthe other examples provided below or throughout the present disclosure.

Example 1 includes the subject matter embodied by a user equipment (UE)configured to transmit a data stream to an Evolved Node B (eNodeB), theUE comprising: at least one antenna port, each antenna port beingconnectable to an antenna capable of transmitting data from the datastream to the eNodeB at one of a plurality of selectable tuning states,the combination of antenna ports and tuning states forming a pluralityof selectable antenna states for the UE; and circuitry configured to:transmit to the eNodeB a first portion of the data stream over a firstantenna state of the plurality; sequentially transmit to the eNodeB atest signal over each antenna state in the plurality; receive from theeNodeB an indication that the test signal transmitted on a secondantenna state of the plurality is stronger at the eNodeB than the testsignal transmitted on the first antenna state; and transmit to theeNodeB a second portion of the data stream over the second antennastate.

In Example 2, the subject matter of Example 1 can optionally include themethod of example 1, wherein the circuitry is further configured to:prior to transmitting each test signal to the eNodeB, transmit arespective Sounding Reference Signal (SRS) to the eNodeB over therespective antenna state, the SRS forming at least a portion of anAntenna Tuning Subframe (ATSF) of a Long Term Evolution (LTE) framestructure.

In Example 3, the subject matter of any one of Examples 1-2 canoptionally include wherein the circuitry is further configured totransmit the test signals and receive the indication from the eNodeBusing protocols of the physical layer.

In Example 4, the subject matter of any one of Examples 1-3 canoptionally include wherein the circuitry is further configured toreceive a modified DCI Format 4 message in a Physical Downlink ControlChannel (PDCCH) to initiate the sequential transmissions of the testsignals.

In Example 5, the subject matter of any one of Examples 1-4 canoptionally include wherein the indication from the eNodeB is a receivedmodified Downlink Control Indicator (DCI) Format 4 message in a PhysicalDownlink Control Channel (PDCCH).

In Example 6, the subject matter of any one of Examples 1-5 canoptionally include wherein the received DCI Format 4 message includes aSounding Reference Signal (SRS) Report field having a valuecorresponding to the second antenna state of the plurality.

In Example 7, the subject matter of any one of Examples 1-6 canoptionally include wherein the received DCI Format 4 message includes aprecoding matrix (PMI) and rank indicator (RI) field having a value thatindicates a best-matched precoding matrix to be used for transmittingthe second portion of the data stream.

In Example 8, the subject matter of any one of Examples 1-7 canoptionally include wherein the circuitry is further configured totransmit the test signals and receive the indication from the eNodeBusing protocols of the upper layer.

In Example 9, the subject matter of any one of Examples 1-8 canoptionally include wherein the circuitry is further configured toreceive an upper layer configuration message from the eNodeB to initiatethe sequential transmissions of the test signals.

In Example 10, the subject matter of any one of Examples 1-9 canoptionally include wherein the received upper layer configurationmessage includes a Sounding Reference Signal (SRS) Report Antenna TuningSubframe (ATSF) Counter field having a value corresponding to one of theantenna states.

In Example 11, the subject matter of any one of Examples 1-10 canoptionally include wherein the SRS ATSF Counter field is incremented foreach of the sequential test signal transmissions.

In Example 12, the subject matter of any one of Examples 1-11 canoptionally include wherein the received upper layer configurationmessage includes a Sounding Reference Signal (SRS) Report Antenna TuningSubframe (ATSF) Counter Reset field having a value directing the UE toreset the SRS ATSF Counter field and begin sequentially transmitting thetest signals to the eNodeB.

In Example 13, the subject matter of any one of Examples 1-12 canoptionally include wherein the circuitry is further configured to: ceasetransmitting to the eNodeB the first portion of the data stream over thefirst antenna state at a first predetermined time; sequentially transmitto the eNodeB the test signal over each antenna state in the pluralitybeginning at a second predetermined time; receive, at a thirdpredetermined time, from the eNodeB an indication that the test signaltransmitted on a second antenna state of the plurality is stronger atthe eNodeB than the test signal transmitted on the first antenna state;and transmit to the eNodeB the second portion of the data stream overthe second antenna state beginning at a fourth predetermined time; ceasetransmitting to the eNodeB the second portion of the data stream overthe second antenna state at a fifth predetermined time; sequentiallytransmit to the eNodeB a test signal over each antenna state in theplurality beginning at a sixth predetermined time; receive, at a seventhpredetermined time, from the eNodeB an indication that the test signaltransmitted on a third antenna state of the plurality is stronger at theeNodeB than the test signal transmitted on the second antenna state; andtransmit to the eNodeB a third portion of the data stream over the thirdantenna state beginning at an eighth predetermined time.

In Example 14, the subject matter of any one of Examples 1-13 canoptionally include at least one transceiver having a radio frequencyfront end (RFFE) configured to apply a selectable tuning state to arespective antenna port; wherein the RFFE selects each tuning state byapplying at least one of a selectable impedance or a selectable apertureto the respective antenna port.

In Example 15, the subject matter of any one of Examples 1-14 canoptionally include memory configured to store instructions forcontrolling the circuitry; and wherein the circuitry includes processingcircuitry configured to execute the instructions stored in the memory.

In Example 16, the subject matter of any one of Examples 1-15 canoptionally include wherein the UE comprises a plurality of antennaports, and further comprising: a plurality of antenna tuner elementselectrically coupled to respective antenna ports, of the plurality ofantenna ports, each antenna tuner element configured to receive a tunercontrol signal that specifies a selected tuning state for the respectiveantenna, each antenna tuner element further configured to receive aradio frequency (RF) signal corresponding to data from the data stream;a plurality of transceivers electrically coupled to respective antennatuner elements, of the plurality of antenna tuner elements, eachtransceiver configured to receive data from the data stream and generatethe respective RF signal; and a multiple-output (MIMO) modemelectrically coupled to the plurality of antenna tuner elements, theMIMO modem configured to select one of the plurality of transceivers,provide data from the data stream to the selected transceiver, andgenerate the tuner control signal for the selected transceiver.

In Example 17, the subject matter of any one of Examples 1-16 canoptionally include a plurality of antennas connectable to respectiveantenna ports, of the plurality of antenna ports.

Example 18 is a non-transitory computer-readable medium containinginstructions which, when executed, perform operations to configure auser equipment (UE) to transmit a data stream to an Evolved Node B(eNodeB), the UE including a plurality of antenna states configured fortransmitting from the UE, the operations to configure the UE to:transmit to the eNodeB a first portion of the data stream over a firstantenna state of the plurality; sequentially transmit to the eNodeB atest signal over each antenna state in the plurality; receive from theeNodeB an indication that the test signal transmitted on a secondantenna state of the plurality is stronger at the eNodeB than the testsignal transmitted on the first antenna state; and transmit to theeNodeB a second portion of the data stream over the second antennastate; wherein the operations to further configure the UE to transmitthe test signals and receive the indication from the eNodeB usingprotocols of one of a physical layer or an upper layer.

In Example 19, the subject matter of Example 18 can optionally includewherein the operations are further configured to: prior to transmittingeach test signal to the eNodeB, transmit a respective Sounding ReferenceSignal (SRS) to the eNodeB over the respective antenna state, the SRSforming at least a portion of an Antenna Tuning Subframe (ATSF) of aLong Term Evolution (LTE) frame structure.

In Example 20, the subject matter of any one of Examples 18-19 canoptionally include wherein the operations are further configured to:cease transmitting to the eNodeB the first portion of the data streamover the first antenna state at a first predetermined time; sequentiallytransmit to the eNodeB the test signal over each antenna state in theplurality beginning at a second predetermined time; receive, at a thirdpredetermined time, from the eNodeB an indication that the test signaltransmitted on a second antenna state of the plurality is stronger atthe eNodeB than the test signal transmitted on the first antenna state;and transmit to the eNodeB the second portion of the data stream overthe second antenna state beginning at a fourth predetermined time; ceasetransmitting to the eNodeB the second portion of the data stream overthe second antenna state at a fifth predetermined time; sequentiallytransmit to the eNodeB a test signal over each antenna state in theplurality beginning at a sixth predetermined time; receive, at a seventhpredetermined time, from the eNodeB an indication that the test signaltransmitted on a third antenna state of the plurality is stronger at theeNodeB than the test signal transmitted on the second antenna state; andtransmit to the eNodeB a third portion of the data stream over the thirdantenna state beginning at an eighth predetermined time.

Example 21 is a method for transmitting a data stream to an Evolved NodeB (eNodeB), the method comprising: transmitting to the eNodeB a firstportion of the data stream over a first antenna state, of a plurality ofantenna states; sequentially transmitting to the eNodeB a test signalover each antenna state in the plurality; receiving from the eNodeB anindication that the test signal transmitted on a second antenna state ofthe plurality is stronger at the eNodeB than the test signal transmittedon the first antenna state; and transmitting to the eNodeB a secondportion of the data stream over the second antenna state; and furthercomprising prior to transmitting each test signal to the eNodeB,transmitting a respective Sounding Reference Signal (SRS) to the eNodeBover the respective antenna state, the SRS forming at least a portion ofan Antenna Tuning Subframe (ATSF) of a Long Term Evolution (LTE) framestructure.

In Example 22, the subject matter of Example 21 can optionally includeceasing transmitting to the eNodeB the first portion of the data streamover the first antenna state at a first predetermined time; sequentiallytransmitting to the eNodeB the test signal over each antenna state inthe plurality beginning at a second predetermined time; receiving, at athird predetermined time, from the eNodeB an indication that the testsignal transmitted on a second antenna state of the plurality isstronger at the eNodeB than the test signal transmitted on the firstantenna state; and transmitting to the eNodeB the second portion of thedata stream over the second antenna state beginning at a fourthpredetermined time; ceasing transmitting to the eNodeB the secondportion of the data stream over the second antenna state at a fifthpredetermined time; sequentially transmitting to the eNodeB a testsignal over each antenna state in the plurality beginning at a sixthpredetermined time; receiving, at a seventh predetermined time, from theeNodeB an indication that the test signal transmitted on a third antennastate of the plurality is stronger at the eNodeB than the test signaltransmitted on the second antenna state, and transmitting to the eNodeBa third portion of the data stream over the third antenna statebeginning at an eighth predetermined time.

In Example 23, the subject matter of any one of Examples 21-22 canoptionally include wherein the test signals are transmitted and theindication from the eNodeB is received the using protocols of a physicallayer.

In Example 24, the subject matter of any one of Examples 21-23 canoptionally include wherein the test signals are transmitted and theindication from the eNodeB is received the using protocols of an upperlayer.

Example 25 is at least one computer readable medium containing programinstructions for causing a computer to perform the method of any one ofExamples 21-24.

Example 26 is an apparatus having means to perform any of the methods ofany one of Examples 21-24.

The Abstract is provided to allow the reader to ascertain the nature andgist of the technical disclosure. It is submitted with the understandingthat it will not be used to limit or interpret the scope or meaning ofthe claims. The following claims are hereby incorporated into thedetailed description, with each claim standing on its own as a separateembodiment.

What is claimed is:
 1. An apparatus of a user equipment (UE), theapparatus comprising: memory; and processing circuitry, the processingcircuitry configured to: encode a first portion of the data stream fortransmission to the eNB over a first antenna of a plurality of antennas;encode a test signal for sequential transmission to the eNB over asecond antenna of the plurality of antennas, the test signal indicativeof a tuning state of a plurality of tuning states for the secondantenna; in response to the test signal, decode a transmit (Tx) antennaselection indicator received from the eNB, the Tx antenna selectionindicator indicating the second antenna of the plurality of antennas foruse in subsequent transmissions; and encode a second portion of the datastream for transmission to the eNB over the second antenna.
 2. Theapparatus of claim 1, wherein the processing circuitry is furtherconfigured to: encode the test signal for transmission to the eNB as asounding reference signal (SRS), the SRS indicative of one of aplurality of antenna states associated with the second antenna.
 3. Theapparatus of claim 2, wherein an antenna state of the plurality ofantenna states is a combination of one of the tuning states and anantenna of the plurality of antennas.
 4. The apparatus of claim 2,wherein the SRS is encoded for transmission within an antenna tuningsubframe (ATSF).
 5. The apparatus of claim 2, wherein the processingcircuitry is configured to: encode a plurality of additional testsignals for transmission to the eNB, each of the additional test signalsassociated with a unique antenna state of the plurality of antennastates.
 6. The apparatus of claim 1, wherein the processing circuitry isconfigured to: decode a downlink control indicator (DCI) messagereceived via a physical downlink control channel (PDCCH), the DCImessage including the Tx antenna selection indicator.
 7. The apparatusof claim 6, wherein the DCI message comprises rank indicator (RI) andprecoding matrix indicator (PMI) associated with the tuning state of thesecond antenna.
 8. The apparatus of claim 6, wherein the Tx antennaselection indicator is an SRS report within the DCI message.
 9. Theapparatus of claim 8, wherein the SRS report is indicative of an antennatuning subframe (ATSF) of a plurality of ATSFs transmitted by the UE,the ATSF associated with one of the plurality of tuning states for thesecond antenna of the plurality of antennas.
 10. The apparatus of claim1, wherein the processing circuitry is further configured to encode thetest signal for transmission using protocols of a physical layer. 11.The apparatus of claim 1, wherein the tuning state of the plurality oftuning states is associated with at least one of a selectable impedanceor a selectable aperture for the second antenna.
 12. The apparatus ofclaim 1, further comprising transceiver circuitry coupled to theprocessing circuitry and the plurality of antennas.
 13. An apparatus ofan evolved Node-B (eNB), the apparatus comprising: memory; andprocessing circuitry, configured to: decode a plurality of test signalsreceived from a user equipment (UE), wherein: each test signal isassociated with a corresponding antenna state of a plurality of antennastates for the UE; and an antenna state of the plurality of antennastates is indicative of a transmit antenna of a plurality of UE transmitantennas and a tuning state of a plurality of tuning states; select anantenna state from the plurality of antenna states based on signalquality characteristics of the received plurality of test signals; andencode the selected antenna state as a transmit (Tx) antenna selectionindicator within a downlink control information (DCI) message fortransmission to the UE.
 14. The apparatus of claim 13, wherein theprocessing circuitry is further configured to: decode the plurality oftest signals as part of a corresponding plurality of antenna tuningsubframes (ATSFs).
 15. The apparatus of claim 14, wherein the processingcircuitry is further configured to: encode an identification of an ATSFof the plurality of ATSFs within the DCI message, wherein the ATSFcorresponds to the selected antenna state.
 16. A non-transitorycomputer-readable storage medium that stores instructions for executionby one or more processors of a user equipment (UE), the instructions toconfigure the one or more processors to cause the UE to: encode aplurality of test signals for sequential transmission to an evolvedNode-B (eNB) using one of a corresponding plurality of antenna states,wherein an antenna state of the plurality of antenna states isindicative of an antenna of a plurality of transmit antennas and atleast one tuning state for the antenna; in response to the sequentialtransmission of the test signals, decode a transmit (Tx) antennaselection indicator received from the eNB, the Tx antenna selectionindicator indicating a transmit antenna of the plurality of transmitantennas for use in subsequent transmissions, and encode a data streamfor transmission to the eNB over the indicated transmit antenna.
 17. Thenon-transitory computer-readable storage medium of claim 16, wherein theinstructions further cause the UE to: encode the test signals fortransmission to the eNB as sounding reference signals (SRSs), each SRSindicative of one of the plurality of antenna states associated with thetransmit antennas.
 18. The non-transitory computer-readable storagemedium of claim 17, wherein the instructions further cause the UE to:encode the SRSs for transmission to the eNB within a correspondingplurality of antenna tuning subframes (ATSFs).
 19. The non-transitorycomputer-readable storage medium of claim 16, wherein the instructionsfurther cause the UE to: decode a downlink control indicator (DCI)message received via a physical downlink control channel (PDCCH), theDCI message including the Tx antenna selection indicator.
 20. Thenon-transitory computer-readable storage medium of claim 19, wherein theTx antenna selection indicator is an SRS report within the DCI message.